3·87
ANSI05000774-3-en.vsd
ANSI05000774 V3 EN
Figure 42: Application of the high impedance differential function on tertiary busbar
Setting example
It is strongly recommended to use the highest tap of the CT whenever
high impedance protection is used. This helps in utilizing maximum CT
capability, minimize the current, thereby reducing the stability voltage
limit. Another factor is that during internal faults, the voltage developed
across the selected tap is limited by the non-linear resistor but in the
unused taps, owing to auto-transformer action, voltages much higher
than design limits might be induced.
Basic data:
Current
transformer ratio:
2000/5 A (Note: Must be the same at all locations)
CT Class: C400 (At max tap of 2000/5)
C400 (At max tap of 2000/5)
Secondary
resistance:
0.5 Ohms (At 2000/5 Tap)
Table continues on next page
Section 3 1MRK504116-UUS C
IED application
150
Application manual
To Next Page
Loading...
